Which battery terminal first

I am curious to which battery terminal should I take off first, positive or negative? When changing a battery I have always taken off the positive first followed by the negative, but when helping a neighbor with his car yesterday, he took off the negative cable to cut power to the electronics.

Any ideas which one to take off first? Does it even matter? Thanks for your input.

Most people beleive its the negative terminal, but basically it doesn’t eally matter. either way you are creating a break in the circuit. There is voltage on both negative and positive circuits.

" Does it even matter?" Not really…If you take the negative off first, there is no danger of shorting your wrench to ground when disconnecting the positive post…First, make sure you don’t have an “anti-theft” radio which needs a reset code if disconnected…

Take off the negative terminal first. From personal experience you don’t want to accidently short the positive terminal to ground while removing it. The wrench I was using to loosen the positive terminal touched the frame and completed the circuit. Fortunately it was a 69 Buick and there were no electronics to fry. Since the negative terminal is already connected to ground and has no voltage, nothing will happened if the wrench touches the frame (ground) while removing the negative terminal.

Ed B.

Negative is first to remove and last to install. To be perfect, remove the grounded terminal first, usually it is the negative one unless you are working on a rare forklift or something.

Exactly right. Ground one off first and on last, for safety against shorting.

A couple months ago, my Delco Pro battery gave up the ghost here in Mexico. I charged it long enough to get it started, then drove it to a place which sells LTH battery, allegedly a better battery in Mexico. The kid reached for the hot lead with his wrench, and I told him, no, and pointed to the ground cable, which he did. I don’t know if he learned anything or just did it to make a customer happy.

Do you need to remove either battery cable to charge the battery? I don’t

I don’t see any comments about removing a battery cable to charge the battery. I do see comments about removing battery cables to change the battery.

I don’t either, EllyEllis. The instructions that came with my battery chargers didn’t suggest disconnecting the terminals. In fact, two of my trickle chargers came with leads that permanently attach to the battery. The only thing they recommend is that if you use the clamps to attach the battery to the charger, you should attach the negative clamp to the body of the vehicle instead of directly to the negative terminal.

Tardis, I think he was just asking, not suggesting anyone said so.

Besides the short circuit insurance issue there is a school of thought that says removing the negative first reduces the chances of a spark happening at the moment the circuit is opened and this spark igniting the hydrogen gas around the top of the battery,sounds like a Mr wizard issue to me.

Whitey, I misread the post. I thot he said that a neighbor removed the negative cable to CHARGE the battery. Where have you been, I haven’t seen much of you lately??

Remove the ground first. It doesn’t matter if you accidently touch the wrench to the frame while you are loosening the ground.
After the ground is open, it no longer matters if you accidently touch the wrench to the frame while loosening the positive.

Years ago, I saw someone with a missing ring finger. He accidently shorted a car battery to ground with his wedding ring and the ring turned red hot and injured the finger so badly that it had to be amputated.

When connecting a battery charger, I connect the positive lead first. There will be no spark because the ground is open.
Then I connect the negative (ground) to the engine block, bumper, or some part of the frame far away from the battery. That way any spark is far away from the battery.

When disconnecting, the ground is removed first and then there is no spark when disconnecting the positive.

What resistive material was the ring made of that made it get so hot? Certainly not a standard gold wedding ring?

(Yes I know that the current flows on the surface of the metal so the solid ring wouldn’t be as good a conductor as braided wire.)

You are underestimating the amount of current that a car battery can supply (for a brief period of time).

A dead short with a basicaly unlimted amount of current avaible (as far as the human body is concerned) made the ring get so hot.

You are right, if the ring was a cigar band it would not have gotten hot.

Ok, I researched this. Don’t have a wedding ring, but I do have access to a car battery. I’m sold.

It’s a bit of a paradox as even a very good conductor(like gold) demonstrates resistive properties when current flows, and it is these resistive properties that cause heat. Resistance occurs when electrons collide as current flows through the conductor. These collisions cause friction, which in turn causes heat.

Elly, I’ve been working for a change. I have a new job.